Drop C lowers every string by one whole step and then drops the lowest string another whole step, giving you C G C F A D.
You can technically use .010 gauge strings in Drop C, but most players find them too loose. Heavier gauges feel firmer and stay more stable.
Switching to heavier strings or tuning significantly lower can affect neck relief and intonation, so some guitars benefit from small setup adjustments.
If you want a specific feel, you can build a custom combination with single guitar strings to get exactly the balance you prefer.